1. Field of the Invention
The present invention generally relates to fuel measuring systems and, more particularly, to an improvement in the air flow regulator of the so-called bubble type fuel measuring systems.
1. Description of the Prior Art
U.S. Pat. No. 4,840,056 to Emilio A. Fernandez et al. describes a fuel measuring system which measures diesel fuel in a fuel tank on a locomotive. In this system, air from the locomotive at 120 to 140 psi is supplied to a regulator and filter to reduce and regulate the pressure to 8 psi. The regulated low pressure air is then supplied to a needle valve which is adjusted to supply a flow of 225 ml/min. to the fuel measuring system. The air regulator and needle valve are typically housed in a common case, which is known in the art as an "air box".
The needle valve is subject of fouling due to contaminants in the air supply, thus requiring an efficient air filter. Both the air filter and the regulator are expensive, adding to the cost of the fuel measuring system.